April Shelby's Memorial fund

A few days ago, I noticed my cat Sam was having a hard time using his litter box. I've been giving him soft foods and things for constipation, but there's no change. I don't think he's managed to get anything out in that time. I'm really starting to worry.
Sam and his sister, Dean wer adopted by myself and my late wife, April V. Shelby. We both swore that we'd keep them together and with us no matter what. Since April passed in May, these two wonderful cats have been keeping me happy and focused on something other than how much I miss her.
I'm on a very fixed income and can't afford a vet visit. So, I'm writing this in hopes of getting enough to cover if I do end up having to take him in. So far Sam's appetite is good, he's drinking, playing and all. But he hasn't made waste in two days. And that's my concern now.
I know, I'm asking a lot, but Sam and Dean mean a lot to me. So anything would be helpful. I'm being precautious. What is left over will go towards future vet visits for both cats.
Anything helps, thank you and God bless you 
Leilani